Nobukazu Okamoto1*, Eiichi Nakamura2, Tetsuro Masuda1, Hitoshi Ito1, Satoshi Hisanaga1 and Takeshi Miyamoto1
1Department of Orthopedic Surgery, Kumamoto University, Japan
2Kumamoto Kaiseikai Hospital, Japan
Mobile-bearing Total Knee Arthroplasty (TKA) is associated with high conformity and low-contact stress. The rotation of the polyethylene insert better replicates natural motion. Improvement in daily activities, such as squatting and kneeling, that require high knee flexion, has reportedly resulted in increased patient satisfaction after TKA. The purpose of this study was to determine whether a mobile-bearing TKA improved functional knee flexion better than a fixed-bearing TKA. We compared the difference in weight-bearing knee kinematics in patients with mobile-bearing and fixed-bearing TKA by performing lunging or kneeling activities. We randomly allocated 40 knees (37 patients) to mobile-bearing TKA (n=20) or fixed-bearing TKA (n=20). Using fluoroscopic imaging, we evaluated knee kinematics during these activities one year postoperatively. There were no differences in maximum knee flexion during lunging or kneeling, or in the total extent of rotation. Due to the external rotation of the polyethylene insert, patients with mobile-bearing TKA had a wider range of absolute external rotation. The position of the medial and the lateral condyles was not different between the two TKAs. The motion of the polyethylene insert in the mobile-bearing TKA did not contribute to an increase in maximal flexion and kinematics during the aforementioned activities. Further comparative research evaluating long-term clinical outcomes is required.
Total knee arthroplasty; Kinematics; Mobile-bearing; Fixed-bearing
Okamoto N, Nakamura E, Masuda T, Ito H, Hisanaga S, Miyamoto T. Comparison of In Vivo Knee Kinematics between Fixed-Bearing and Mobile-Bearing Total Knee Arthroplasty during Deep Knee Bending Activities. Clin Surg. 2019; 4: 2513..